Process for the manufacture of yeast



' Nov. 6,192 3. v

" 'UNITED STATES PATENT OFFICE.

FRIEDRICH HAYDUCK, OF WILMERSDORF, GERMANY, ASSIGNOR TO. THE FLEISGH .MANN COMPANY, OF NEW YORK, N. Y., A CORPORATION OF OHIO.

PROCESS FOB THE MANUFACTURE OF YEAST.

No Drawing. Original 11.0. 1,449,111, dated March 20, 1923, Serial no. 420,833, filed October so, 1920;

oammu. cam-ran UNDER THE PROVlISIONS or THE M31 or Manon a, 1921, 41 s'i'ii'r. 1 ,1318.)

Application for reissue filed July 20, 1923. Serial 1T0.- 652,818.

T 0 all whom it may concern: I

Be it known that I, Fini-ionioii HAYDUCK, citizen of Germany, residing at \Yilmersdorf, Germany, have invented certain new 6 and useful Improvements in Processes forthe Manufactur'e'of Yeast (for which application for patent wasfiled in Germany December 23,: 1915, Patent \No. 303,311), of

v which the following is a specification.

l0 This invention relates to aprocess for the manufacture of yeast and more particularly toa process in which the yeast to be used as seed yeast is given a preliminaryfermen tation. An object of this invention is to provide an improved process of manufacture in which seediyeast is. treated-in a wort containing sug r material and inorganic salts in order to render it devoid of infection.

Yeast growing processes in which nu- .trient solutions comprising sugar material and inorganic yeast nutrient salts are em ployed exclusively, are known. Examples of such processes are described in my co- :5 pending applications Serial Nos. 42 ,829 and 420,830, corresponding respectively to Ger-- man Letters Patent Nos. 300,663 and 303,251 In these processes it is preferable to render innocuousthe excess of acid liberated from the nutrient salts, by adding a neutralizing agent, for example, chalk, as taught in my co-pending application Serial No. 420,830. By this step of neutralization such processesare made to give veryhigh yields of yeast.

85 In the practice of neutralization, however,

thereis a disadvantage in that the yeast.

growth takes place in a nearly neutral or but weakly acid nutrient solution. As a consequence yeast grown in such worts has ,little protection against the growth of infecting micro-organisms and it is desirable therefore to protect the yeast against infection, or the action of such undesirable micro-organisms. used as seed yeast, is treated with a qua'n tity of sulphuric acid sufficient to kill all the infecting organisms.

In the practice of my present invention the step, by which such organisms are killed and the yeast rendered devoid of infection, is carried out in a manner such that sulphuric acid per se is not used, but only the action To this end yeast,to beof its acid radical employed. This is accom'plis'hed by causing the yeast to undergo a preliminary fermentation in an aqueous nutrient solution containing sugar material and inorganic yeast nutrient salts but withoutthe addition of chalk.

\Vhen east is multiplying in such a nutrient so ution, inorganic acid radicals are continually being released from the salts employed, forming a steadily increasing amountof acid in the solution. The acid thus formed is permitted to accumulate until a degree of acidity is attained which removes from the yeast the undesired infecting organisms without the direct addition of aiiv sulphuric acid.

The following, is an example of the manner in which the process of this invention is carried out:

A nutrient solution is made up. comprising sugar or molasses and inorganic yeast nu- The proportions in which trient salts. M these nutrients are to be used may be taken, for example, as set'forth in my co-pnding application Serial No. 420,829, whi'ch are as follows: sugar 100 parts dissolved in tap water, ammonium sulphate 6 parts, animoniuni dihydrogen 3 phosphate 2 parts, potassium sulphate Q-tparts, gypsum 2% parts. and magnesium sulphate 2% parts, the whole being made up with water'to a total of 6,500 to 7,000 parts. As further examples, the proportions of nutrients to be dissolved in water may be taken as set forth in my copending application Serial. No. 420,833, which are as follows: sugar 100 parts, ammonium sulphate 40 parts, acid potassium phosphate 9 parts, magnesium sulphate 1 part; or molasses- (containing %sugar) 100 parts, ammonium. sulphate 10 parts. superphosphate (having 18% water soluble phosphoric acid) 10 parts, magnesium" sulphate 0.5 parts.

Having prepared one ofthese, or a similar nutrient solution, the next step is to take a I until the requireddegree of acidity is atmately 3 i corresponding 'to "a sulphuric tained (this degree acidity is approxi acid content of approximately .O. 125%) after which thecontents of the preliminary fermentation vat are'transferred to the main [vat where the remainder of the nutrient solution is added. Here yeast propaga-. ,tion is carried on with aeration, the -re- 'quired amount of chalk as a neutralizing I :all

agent being added.

A process of, treating artificial yeast (kunsthefesuch asbub or sourstock) in distilleries so that the lactic acid is graduneutralized by means of ammonia, .in or er to providethe yeast with nitrogeneous nourishment, is known. It may-be assumed q that the yeast againsets free some lactic acid from the ammonium salts formed in such process. ,Since,-however the lactic acid yeast by a preliminary fermentation in an; acidified sugar solution containing inorganic is progressively neutralized, whereas the lib erated sulphuric acid is purposely left un-- neutralized, in the process of my presentinvention, up 'to the desired degree, there is 'in this respect "cleartechnical difference.

Furthermore, the step of freeingl yeast cation.

" fermentation by the addition of sulphuric from infection in a so-called pun acid is old; also that of regeneratingwaste 'salts, is known. 'In the present process, ho wever,-no ulphuric acid per se' is added, recourse bein had for sterilization only ,tothe action 0 the inorganic acid" liberated frornxthe nutrient salts b the growing yeast.

, The well known fact th influenced by preliminary neutralization of the substances having an acid reaction contained in the original fermentationliquid,

has not led (previous to my invention herein referred to.) to a processdealing with a systematic neutralization of the acids, as the industry is accustomed to the growth of 'yeast in acid solutions andtherefore could not expect an important. increase in the yield of east' by the neutralization of the acids.

avingdescribed my invention, what I claim as new and desire to secure by Letters- Patent,is': 1 i

1. The process' which comprises causing yeast to un ergo a preliminary fermentation in an aqueous nutrient solution comprising sugar material at the life and fermenta-tion activity of theyea'st is favorably of manufacturing east" and inorganic yeast nutrient salts, permitting the accumulation of liberated acid dur.

ing such-preliminaryfermentation to an extent suiiiclent to afford substantial protection for the yeast against infecting micro-or- 'ganisms, and thereafter using the treated yeast as seed yeast for propagating pur-.-

poses in a nutrient solution comprisingsugar, material and inorganic yeast nutrlent salts;

the propagation being effected with neuof the liberated acid. y

2. The process of 'manufacturingyeast which comprises causing yeast to undergo a preliminary fermentation in an aqueousnutrient solution containing inorganic east nutrlient salts, permitting the accumu ation of liberated acid during such ipreliminary fermentation ta'an extent su substantial protection. for the yeast' against infecting micro-organisms, .and thereafter using the treatedyeast as seed yeast for propagatin purposes in a suitable. nutrient solution; t e propa ation being effected,

with neutralization o the deleterious excess of acidv which is liberated.

3. The process of manufacturing yeast which comprises causing yeast to undergo a preliminary fermentation in.an aqueous nutrient solution containing sulphates, .per- .mitting the accumulation of liberatedflacid tion for the yeast against infecting microorganisms, and thereafter using the treated yeastas seed yeast for propagating purposes in a nutrient solution comprising sugar material, inorganic yeast nutrient salts and an acid neutralizing-agent.

4. In the process of manufacturing compressed bakers yeast, the stepsof preparing seed yeast adapted for propagating purposes in nutrient solutions comprising sugar mater'ial and inorganic salts, which comprise;

causing yeastto undergo a preliminary fermentation in a nutrient solution comprising sugar material and inorganic yeast nutrient salts, and permitting the accumulation of liberated acid'during suchpreliminary fermentatio n to an extent sufficient to afford substantial protection for the yeast against infecting micro-organisms.

In testimony whereof, I have afiixed my signature;

. FRIEDRICH HAYDUCK- '.'during uch. preliminary fermentation to an extent sufficient to afford substantial protec-' 65 tralizati'on of at least a substantial portion 

